Safety exhaust system for the engine compartment of a boat

ABSTRACT

Two basic embodiments of the safety exhaust system are provided. In one embodiment, switch means are provided in the fuel inlet to the gas tank of the engine. These switch means are actuated by removal of the gas cap to start a blower fan motor in the engine compartment to exhaust any fumes which collect therein during a fueling operation. The blower fan is deenergized upon replacement of the gas cap. In the other embodiment, the blower fan is energized by the ignition switch in one position to exhaust any fumes from the engine compartment before the engine is started. Means are provided to prevent energization of the engine starter motor until the blower fan has run for a preselected time interval to thereby assure proper ventilation of the engine compartment before the engine is started. The two embodiments may be integrated into a single safety exhaust system.

United States Patent [151 3,652,868

Hunt [451 Mar. 28, 1972 [54] SAFETY EXHAUST SYSTEM FOR THE 2,019,393 10/1935 Carah ..340/280 ENGINE COMPARTMENT OF A BOAT Harold P. Hunt, 432 Madison Road, County Club Acres RRl, Delray Beach, Fla. 33444 Filed: Feb. 4, 1970 Appl. No.: 8,587

Inventor:

References Cited UNlTED STATES PATENTS 1/1970 Hoffman, Jr ..307/9 4/1967 Van Ranst ...l23/179 A 10/1950 Zurit et a1 ..307/l0 9/1946 Olson ..200/6l.76

Primary Examiner-Herman J. Hohauser AttorneyWhittemore, l-lulbert & Belknap [57] ABSTRACT Two basic embodiments of the safety exhaust system are provided. In one embodiment, switch means are provided in the fuel inlet to the gas tank of the engine. These switch means are actuated by removal of the gas cap to start a blower fan motor in the engine compartment to exhaust any fumes which collect therein during a fueling operation. The blower fan is deenergized upon replacement of the gas cap. In the other embodiment, the blower fan is energized by the ignition switch in one position to exhaust any fumes from the engine compartment before the engine is started. Means are provided to prevent energization of the engine starter motor until the blower fan has run for a preselected time interval to thereby assure proper ventilation of the engine compartment before the engine is started. The two embodiments may be integrated into a single safety exhaust system.

13 Claims, 10 Drawing Figures PATENTEDMAR28 I912 I 3 652, 868

SHEET 3 [1F 3 INVENTOR HAROLD E A a/V7 BY l 7'7 4' JMMW Q A ORNEY SAFETY EXHAUST SYSTEM FOR THE ENGINE COMPARTMENT OF A BOAT BACKGROUND OF THE INVENTION The relatively recent advent of mass use of power boats driven by inboard motors has resulted in a number of serious accidents caused by explosion of combustible gases in the closed engine compastment. A blower fan is provided in such engine compartments to exhaust potentially explosive fumes therefrom. However, some boat operators have been negligent in the use of the blower fan causing the above-mentioned serious accidents.

There are two relatively critical times when the blower fan should be used. One of these times is during the fueling of the gas tankassociated with the engine. At such times, explosive gas fumes may escape into the engine compartment and the blower fan should be operated before the engine is restarted after the fueling operation. The second critical time for use of the blower fan is after the engine has been stopped for any reason and allowed to remain stopped for a period of time. Explosive fumes may also collect in the engine compartment at this time because this compartment is normally vented by motion of the boat and when the engine is stopped, this natural ventilation ceases.

In accordance with the present invention, safety exhaust means are provided to actuate the blower fan at both critical periods, namely during the fueling operation and after the engine has been stopped.

SUMMARY OF THE INVENTION The safety exhaust system for the engine compartment of a boat, in one embodiment, comprises fuel inlet means having a gas cap which is movable to a first position to close the inlet means and movable to a second position to open the inlet means. Switch means are associated with the inlet and fuel cap. The switch means includes a switch actuator. The fuel cap is operatively connected to the switch actuator to cause opening of the switch means by the actuator when the fuel cap is in the first position and to cause closure of the switch means by the actuator when in the second position. An electrically operated blower fan is mounted to exhaust fumes from the engine compartment. Electrical circuitry is connected between the blower fan and electric power means. The switch means is connected in this electrical circuitry and is operative upon movement of the fuel cap to energize or deenergize the blower fan.

In another embodiment, the safety exhaust system comprises an ignition switch which has a first position and a second position. An electrically operated blower fan is mounted to exhaust fumes from the engine compartment. An electrical starter motor is provided for starting the boat engine. First electrical circuitry connects the blower fan to a source of electric power upon actuation of the ignition switch to the first position. Second electrical circuitry connects the starter motor to the electric power upon actuation of the ignition switch to the second position. Electrically actuated stop means prevents actuation of the ignition switch to the second position immediately following actuation thereof to the first position. Electrical timer means are provided. The first electrical circuitry connects the timer means to the electrical power and initiates operation of the timer means upon actuation of the ignition switch to the first position. The timer means is effective to actuate the stop means to permit actuation of the ignition switch to the second position after a preselected time interval. This system may be combined with the system of the first embodiment to provide an integrated safety exhaust system.

IN THE DRAWINGS:

FIG. 1 is a side elevational view of the rear portion of a boat hull with portions broken away to illustrate the placement of the boat engine and exhaust fan;

FIG. 2 is a schematic view of one embodiment of an electrical circuit for a boat for venting the accumulated fumes before engine start-up in accordance with the present invention;

FIG. 3 is a view of a gas cap switching construction and associated electrical circuitry in accordance with another embodiment of the invention;

FIG. 4 illustrates the gas cap construction of FIG. 3 in the closed position;

FIG. 5 is a plan view of the gasoline inlet with the cap removed;

FIG. 6 is a sectional view taken substantially along the line 6-6 of FIG. 5 looking in the direction of the arrows and with the cap in place;

FIG. 7 is a view illustrating another embodiment of a gas cap switching construction and associated electrical circuitry;

FIG. 8 is a view of the gas cap construction of FIG. 7 illustrating the cap in the raised position;

FIG. 9 is a sectional view illustrating the mercury-type switch of the FIG. 7 gas cap in the open position; and

FIG. 10 is a sectional view of the mercury-type switch in the closed position.

Referring first to FIG. 1, the boat hull 10 includes a deck 12 which overlies an engine compartment 14. An internal combustion engine 16 is mounted within the compartment 14 to provide the driving power for the hull. A blower or fan 18 is mounted in the vertical wall 20 forming one wall of the compartment 14. Preferably, the electrical components of the fan motor, namely, the rotor and stator parts, are mounted in a housing 22 placed on the reverse side of the wall 20 and insulated from the compartment 14 so that any sparks generated by the fan motor cannot ignite fumes within the engine compartment. The fan blade construction is provided in a housing 24 within the compartment 14 and directed to blow fumes out of the compartment through a series of vent ports 26 provided in the side of the hull. In accordance with the invention, the fan 18 is energized to exhaust any combustible fumes from the compartment 14 every time that the engine 16 has been stopped and before it is restarted.

Referring now to FIG. 2, it will be noted that an ignition switch 28 is provided as a four-position switch. The switch 28 includes the usual key-operated cylinder 30 which is actuated by insertion of the proper key 32. Movement of the cylinder 30 to any one of four positions will cause the switch arm, indicated by the dotted line 34, to be positioned at one of the four positions. The position to the extreme left as viewed in FIG. 2 includes one contact 36 which is connected by a lead 38 to the auxiliary circuits 40, such as running lights, shortwave radio and the like. The circuits 40 are grounded by lead 42. Another lead 44 extends from the contact 36 to one side of a pair of lamps 46, 48 connected in parallel by leads 50, 52. These lamps are indicator lamps to advise the boat operator whether or not the fan 18 is energized as will be later explained. The fan may be energized automatically by means of the circuitry of the present invention or it may be energized by means of a separate manual switch. Therefore, it is desirable to have the indicator lamps 46, 48 energized in all operative positions of the switch 28.

The second position of the switch 28 includes a single contact 54 which is a dead end contact. In this position, all power provided through the switch 28 is terminated.

The third position of the switch includes a pair of contacts 56, 58. The switch arm 34 closes a circuit through both of the contacts 56, 58 when in the third position. Leads 60, 62 connect contact 56 to lead 38 to thus energize the auxiliary circuits 40 and the lamps 46, 48 when the switch is in the third position. The second contact 58 is connected by a lead 64 to a heating element 66. The heating element 66 is placed physically adjacent to a bi-metal strip 68 which acts as a switch arm between contacts 70, 72. When bi-metal strip 68 is cold, it deforms to the position illustrated in FIG. 2 to make contact with contact 72. When the element 66 is energized, the heat generated thereby causes the bi-metal strip 68 to deform in a direction towards the second contact 70 and, after a period of time, make contact therewith. The action of the strip 68 is such that, when a certain temperature is reached, it will move virtually immediately from one contact position to the other without a substantial intervening time interval. The other end of the heating element 66 is connected by lead 74 to one end of the strip 68 to provide a connection therethrough to power.

A lead 82 extends from the contact 72 to one side of the fan 18. The other side of the fan is grounded by lead 84. Consequently, it will be appreciated that when the strip 68 is cold and assumes the position illustrated in FIG. 2, a connection is made from the switch arm 34 to the fan 18. The switch arm 34 is connected to a suitable source of power, such as the conventional storage battery 78, by means of leads 76,80. The negative side of the battery 78 is grounded by lead 86 as is conventional. When the bi-metal strip 68 is heated sufficiently, it will deform and make contact with the contact 70. This opens the circuit through the fan 18 thus turning the fan off. The length of time that it takes for the heating element 66 to sufficiently heat the bi-metal strip 68 to break the circuit to the fan 18 is set in terms of the wattage of the element 66 and physical characteristics of strip 68 so that a sufficient time interval will elapse to assure that any dangerous accumulation of fumes will have been exhausted from the compartment 14 before ignition of the engine takes place.

During operation of the fan 18, a vane-type switch 88 is actuated to indicate that the fan 18 is energized. The lamps 46, 48, which are in the circuit of the switch 88, are conveniently provided for viewing by the operator of the boat as, for example, on the usual dashboard provided on the bridge. The lamps are different colors. The lamp 46 may, for example, emit a red light indicating that the fan is off or not working, while the lamp 48 may emit a white light indicating that the fan is energized. As will be noted, the leads 50, 52 are connected, respectively, to contacts 90, 92 of the switch 88. The other set of contacts 94, 96 are connected to ground via leads 98, 100. A contact arm 102 is biased by spring 104 to close the contacts 90, 94. Thus the circuit is completed through lamp 46 and, with the fan 18 deenergized, and the switch arm 34 making contact with contacts 36 or 56, the lamp 46 will be energized indicating to the operator that the fan is not in operation. When the fan 18 is in operation, the airflow is directed against the arm 102 as indicated by the arrow 106 causing the arm 102 to compress the spring 104 and close the circuit through contacts 92, 96. If the fan does not work, the lamp 46 will remain lit and indicate to the operator that he must check the fan. If the fan is working, the white lamp 48 will be energized indicating to the operator that the fan is in operation. It is most important that this indication be made during the time when metallic strip 68 closes a circuit to the fan 18. However, it is of interest to the operator at other times in operation of the boat to determine whether or not the fan is on. Whenever the fan is turned off, the arm 102 is biased by the spring 104 back to the position illustrated in FIG. 2 to again energize the lamp 46 apprising the operator that the fan is in the off condition.

When the bi-metal strip 68 makes contact with the contact 70, it closes the power circuit through coil 108 ofsolenoid 1 via leads 112, 114. Energization of the coil 108 causes retraction of plunger 116. The solenoid 110 is mounted adjacent to the switch 28. The plunger 116 is extended towards and away from a stop element 118 which is mounted on the switch cylinder 30 and rotates therewith. A stop surface 120 on the element 118 prevents movement thereof beyond the plunger 116 when the plunger is in the extended position. The plunger is in the extended position when the coil 108 is deenergized. This arrangement prevents movement of the switch arm 34 to its fourth position to start the engine 16 until retraction of the plunger 116. The plunger 116 is, of course, retracted upon movement of the strip 68 to make contact with contact 70. At this point, the fan 18 has been in operation for a sufficient length of time to exhaust dangerous fumes from compartment 14 and it is safe to start the engine.

As will be noted, two contacts 122, 124 are provided in the fourth, or start, position. A lead 126 extends from the contact 122 into connection with the junction of the leads 60, 62 to provide power for the auxiliary circuits 40 in the start position and also to energize the lamp 46. A lead 128 extends from the other contact 124 to one side of the starter motor 130. The other side of the starter motor 130 is grounded by lead 132. Thus, when the switch 28 is actuated to its fourth position, the starter motor is energized through the battery 78 and turns over the engine. As will be noted, the ignition system per se is not incorporated into the present circuit. The incorporation of the ignition system in this circuit is not necessary because the high voltage spark necessary for ignition cannot occur unless the engine is turned over to thereby actuate the generator.

When the engine is stopped, the element 118 is turned in the reverse direction. The plunger 116 will again be extended as soon as the strip 68 cools sufficiently to make contact with the contact 72 thus deenergizing the solenoid coil 108.

An auxiliary start switch 136 is provided to bypass the safety mechanism thus described. One side of the switch 136 is connected to battery 78 via lead 138. The other side of the switch 136 is connected to the starter motor via lead 140 which makes the connection with lead 128 beyond the contact 124. The emergency switch 136 is provided for those occasions where the engine must be started immediately for reasons which override the safety precautions in connection with the exhausting of fumes from the motor compartment. Such a situation may occur, for example, when the engine has been stopped and the boat is drifting and it is suddenly realized that a collision with another boat is imminent. The operator of the boat is, in such cases, able to make a judgment as to which danger is greatest. He may at the same time take precautionary measures to vent the chamber 14 by opening the usual hatch cover associated therewith and starting the fan 18 by separate means. The separate means includes a switch 142 one side of which is connected to power by lead 144 and the other side of which is connected to lead 82 via lead 146 to thereby bypass the heater 66 and metallic strip 68. By this means, the fan 18 may be energized at any time desired.

FIGS. 3 through 6 illustrate an embodiment of the invention which is adapted to specifically exhaust dangerous fumes from the engine compartment 14 during periods when fuel is being taken on. This embodiment may be incorporated into the circuitry of FIG. 2 if desired. When fuel is being taken on, pure gasoline fumes may easily collect within the engine compartment and thus cause a dangerous condition to exist if not exhausted before ignition of the engine takes place.

As will be noted, the circuitry of FIG. 3 is adapted for use in connection with a switch structure incorporated in the outer end of gasoline inlet tube 148. The inlet tube 148 extends into fluid communication with the interior of gas tank 150 and has a central opening 152 through which the nozzle of a gasoline pump hose is extended for filling the tank with gasoline. The exterior portion of the tube 148 is externally threaded for threading engagement with internally threaded gas cap 154.

A switch structure 156 is mounted peripherally of the opening 152 in opening means provided in the wall of inlet tube 148. The switch 156 includes a pair of contact arms 158, 160 on the outer ends of which are mounted contacts 162, 164. The arms 158, 160 are embedded in the inlet tube, portions of which are fabricated of electrically insulating material 166. An arcuate re-entrant opening 168 is provided in the portion 166. The arms 158, 160 extend into the opening 168 from opposite sides thereof. A spring biased actuator 170 is provided within the opening 168. The actuator 170 has tabs 172, 174 which engage lips 176, 178 to thus retain the actuator within the opening 168. The actuator has a recess 180 in the lower portion thereof which receives a spring 182. The other side of the spring engages the bottom 184 of the opening 168. The spring 182 biases the actuator outwardly of the opening 168 towards the position illustrated in FIG. 3.

An arcuate slot 186 is provided extending radially inwardly from the exterior periphery of the actuator 170. An arcuate electrically conductive bar 188 is mounted on the bottom surface 190 of the slot 186. The ends of the bar 188 are in alignment with the contacts 162, 164 of the arms 158, 160. As will be noted, the actuator 170 is fabricated of an electrically insulating material so that the only electric path provided by the bar 188 is along its length.

Referring to FIG. 3, it will be noted that a lead 192, 194 extends from each of the arms 158, 160 through the material of the inlet tube. One lead 192 is connected to one side of the motor of a blower fan 196. The other side of the fan 196 is connected to the positive side of a source of power such as the battery 200.

When the gas cap 154 is unthreaded from the inlet tube for filling of the gas tank, the actuator 170 is biased upwardly as shown in FIG. 3 whereby the contacts 162, 164 make contact with the bar 188. This closes a circuit through the fan motor to thereby energize the fan and cause it to exhaust fumes from the engine compartment in which it is located. The fan will be energized as soon as the gas cap is off. This means that the fan will be energized during the period of'time when gasoline is pumped into the gas tank, thus avoiding the danger of gasoline fumes collecting in the engine compartment. When the cap 154 is screwed onto the inlet tube, the inner surface 202 contacts the actuator 170 depressing it against the action of the spring 182 and thus breaking the connection between contacts 162, 164 and the bar 188. This causes deenergization of the fan 196. A separate switch 204 is provided in lead 206 extending between the lead 192, 194 to permit energization of the fan 196 as desired. The basic circuit of FIG. 2 may optionally be substituted for the switch 204.

An indicator system similar to that of FIG. 1 is provided. Lamps 208, 210 are connected in parallel between contacts 212, 214 of vane-type switch 216 and ground. The lamp 208 serves to warn when the fan is deenergized and the lamp 210 serves to indicate when the fan is energized. The switch 216 has a second set of contacts 218, 220 interconnected by lead 222. The lead 224 extends from contact 220 to the lead 194 to thereby connect the switch 216 to power. An on-off switch 226, which may be incorporated into the ignition switch, is provided in lead 224 to permit disconnecting the lamps from the source of power when the boat is not being used. As will be appreciated, when fan 196 is actuated, it directs the stream of air in the direction of arrows 228 which impinge upon spring bias switch arm 230 to break the circuit through lamp 208 and make the circuit through lamp 210 thus advising the operator that the fan is energized. Upon deenergization of the fan, the arm 230 returns to its normal position and re-energizes lamp 208 to warn that the fan is not being used.

FIGS. 7 through illustrate a gas cap switching system similar in function to that illustrated in FIGS. 3-6 and which may be incorporated into the basic circuit of FIG. 2 in the manner described in connection therewith.

A cup-shaped gas cap 232 is pivotally mounted to an outwardly extending inlet tube 234 by means of a pin 236. An overcenter spring 238 is provided to bias the gas cap 232 to either the closed position illustrated in FIG. 7 or the open position illustrated in FIG. 8 depending upon the angular position of the gas cap.

A mercoid-type switch 240 is secured within the gas cap 232. The switch 240 comprises a closed vessel 242 which contains a charge 244 of electrically conductive liquid, primarily mercury. A pair of leads 246, 248 extend from the upper portion of the vessel 242 and have exposed contacts 250, 252 within the vessel. As will be noted, with the gas cap 232 in the closed position, the vessel 242 is oriented at a downward angle whereby the charge 244 flows by gravity to the lower end of the vessel and out of contact with the contacts 250, 252 as shown in FIG. 9. When the gas cap 232 is tilted upwardly as in FIG. 8, the vessel 242 assumes the position illustrated in FIG. 10 where the charge 244 flows to the opposite end thereof and bridges the contacts 250, 252 to complete a circuit between leads 246, 248.

The leads 246, 248 extend from the vessel 242 downwardly through a vertical opening 254 in the outer periphery of the inlet tube 234, and thence through a small opening 256 in the side wall portion 258 into connection with the circuit 260 lllustrated in FIG. 7.

The lead 246 is connected to the positive side of battery 262 which is grounded on the other side by lead 264. The lead 248 is connected to one side of the motor of blower fan 266. The other side of the motor is grounded by lead 268. A manual switch 270 is provided in lead 272 across leads 246, 248 to permit energization of the blower fan 266 at any time desired. As will be appreciated, tipping of the gas cap 232 upwardly as in FIG. 8 to permit fueling through the inlet opening 274 results in closing the circuit to power through the fan 266 to thereby energize the fan and exhaust fumes from the motor compartment in which the fan is located during the fueling operation. After the fueling operation and closure of the gas cap 232, the vessel 242 will assume the position illustrated in FIG. 9 and thereby open the circuit through fan 266.

A lead 276 extends from power lead 246 to a vane-type switch 278 of the type previously described. An on-off switch 280 is provided in this lead. The switch 278 controls operation of parallel connected warning lamps 282, 284 as previously described. The fan 266 directs a stream of air in the direction of the arrows 286 to cause actuation of the switch arm 288 of the switch 278 as described hereinbefore.

In addition to direct operation of the blower fan by the gas cap switches shown in FIGS. 3 and 7, these switches may be used to trigger a time delay circuit to maintain the blower fan in operation for a period of time after the gas cap has been replaced.

What I claim as my invention is:

1. A safety exhaust system for the engine compartment of a boat comprising a fuel inlet, a fuel cap movable to a first position to close said fuel inlet and movable to a second position to open said fuel inlet, switch means associated with said fuel inlet and fuel cap, said switch means including a switch actuator, said fuel cap being operatively connected to said switch actuator to cause opening of the switch means by the actuator when the fuel cap is in said first position and to cause closure of the switch means by the actuator when in said second position, an electrically operated blower fan mounted to exhaust fumes from the engine compartment, electric power means, electrical circuitry connected between said blower fan and electric power means, said switch means being connected in said electrical circuitry and operative upon movement of said fuel cap to energize or deenergize the blower fan.

2. A safety exhaust system as defined in claim 1, and further characterized in that said electric switch means comprises a mercury switch mounted in said fuel cap, said fuel cap being pivotally mounted on the fuel inlet, the charge of mercury in said switch defining the switch actuator, pivoting of said fuel cap to said first position to close the fuel inlet causing said charge to flow in a direction to open the switch and pivoting of said cap to the second position to open the fuel inlet causing the charge to flow in a direction to close the switch.

3. A safety exhaust system as defined in claim 2, and further characterized in that said mercury switch comprises a vessel enclosing said charge of mercury, said vessel being mounted in said cap with one end thereof lower than the other end when the cap is in the first position, the pair of contacts within the vessel located adjacent the other end and above the level of the charge when the cap is in the first position, leads extending from said contacts externally of the vessel into connection with the electrical circuitry, pivoting of said cap to the second position causing the mercury charge to flow to the other end of the vessel and complete an electrical circuit through said contacts.

4. A safety exhaust system as defined in claim 1, and further characterized in that said switch means is mounted in said fuel inlet, said fuel inlet included an opening for injection of fuel, a recess adjacent said opening, fixed contact means extending into said recess, said actuator being a member slidably received in said recess, spring means biasing said actuator outwardly of the recess to a position where a portion thereof extends from the fuel inlet, contact means carried by said actuator to close said fixed contact means upon biasing of the actuator to said last mentioned position by the spring, said fuel cap being effective to depress the actuator when moved to the first position thereof to open the fixed contact means,

5. A safety exhaust system as defined in claim 4, and further characterized in that said fixed contact means includes a pair of spaced apart contacts, the contact means on the actuator including an electrical conductor which engages both of said contacts upon biasing of the actuator by. the spring to thereby close the circuit through the fixed contacts.

6. A safety exhaust system as defined in claim 1, and further characterized in the provision of a pair of electrical signalling devices connected in parallel, a double-throw, double pole vane-type switch interposed between said signalling devices and said electric power means, said vane-type switch normally biased in one direction to close a circuit through power to one of the signalling devices, said vane-type switch being positioned in the flow path of the blower fan and operative upon impingement of gas flow thereon from the fan to open a circuit through power to said one signalling device and close a circuit through power to the other signalling device, and operative upon deenergization of the blower fan to revert to the original position.

7. A safety exhaust system as defined in claim 1, and further characterized in the provision of separate additional switch means in said electrical circuitry operative upon closure thereof to energize the blower fan.

8. A safety exhaust system as defined in claim 7, and further characterized in that said separate additional switch means comprises an ignition switch having a first position and a second position, an electric starter motor for starting the boat engine, first electrical circuitry connecting said blower fan to said electric power upon actuation of said ignition switch to the first position, second electrical circuitry connecting said starter motor to said electric power upon actuation of said ignition switch to the second position, electrically actuated stop means preventing actuation of the ignition switch to the second position immediately following actuation thereof to the first position, electrical timer means, said first electrical circuitry connecting said timer means to said electrical power and initiating operation thereof upon actuation of said ignition switch to the first position, said timer means effective to actuate said stop means to permit actuation of the ignition switch to the second position after a preselected time interval.

9. A safety exhaust system for the engine compartment of a boat comprising an ignition switch having a first position and a second position, an electrically operated blower fan mounted to exhaust fumes from the engine compartment, an electric starter motor for starting the boat engine, electric power means, first electrical circuitry connecting said blower fan to said electric power upon actuation of said ignition switch to the first position, second electrical circuitry connecting said starter motor to said electric power upon actuation of said ignition switch to the second position, electrically actuated stop means preventing actuation of the ignition switch to the second position immediately following actuation thereof to the first position, electrical timer means, said first electrical circuitry connecting said timer means to said electrical power and initiating operation thereof upon actuation of said ignition switch to the first position, said timer means being effective to actuate said stop means to permit actuation of the ignition switch to the second position after a preselected time interval, said electrically actuated stop means comprising an electric solenoid having an extensible and retractable plunger, and a stop element on the ignition switch, said solenoid plunger being in registry with the stop element when the solenoid is deenergized and moving out of registry with the stop element upon energization of the solenoid to permit actuation of the ignition switch to the second position.

10. A safety exhaust system as defined in claim 9, and

further characterized in that said timer means comprises an electrical heater element in said first circuitry, a bi-metal strip in series with said heater element and located adjacent thereto to receive heat therefrom, said bi-metal element having a portion normally closing the circuit through said blower fan, said bi-metal element deflecting after being subjected to heat from the heating element for a predetermined time to open the circuit through the blower fan and close the circuit through the electrically actuated stop means.

11. A safety exhaust system as defined in claim 9, and further characterized in the provision of an emergency switch between said starter motor and electric power bypassing the ignition switch to permit energization of the starter motor under emergency conditions.

12. A safety exhaust system as defined in claim 9, and further characterized in the provision of a pair of electrical signalling devices connected in parallel, a double-throw, double-pole vane-type switch interposed between said signalling devices and said electric power means, said vane-type switch normally biased in one direction to close the circuit through power to one of the signalling devices, said vane-type switch being positioned in the flow path of the blower fan and operative upon impingement of gas flow thereon from the fan to open a circuit through power to said one signalling device and close a circuit through power to the other signalling device, and operative upon deenergization of the blower fan to revert to the original position.

13. A safety exhaust system as defined in claim 9, and further characterized in the provision of separate additional switch means in said electrical circuitry operative upon closure thereof to energize the blower fan. 

1. A safety exhaust system for the engine compartment of a boat comprising a fuel inlet, a fuel cap movable to a first position to close said fuel inlet and movable to a second position to open said fuel inlet, switch means associated with said fuel inlet and fuel cap, said switch means including a switch actuator, said fuel cap being operatively connected to said switch actuator to cause opening of the switch means by the actuator when the fuel cap is in said first position and to cause closure of the switch means by the actuator when in said second position, an electrically operated blower fan mounted to exhaust fumes from the engine compartment, electric power means, electrical circuitry connected between said blower fan and electric power means, said switch means being connected in said electrical circuitry and operative upon movement of said fuel cap to energize or deenergize the blower fan.
 2. A safety exhaust system as defined in claim 1, and further characterized in that said electric switch means comprises a mercury switch mounted in said fuel cap, said fuel cap being pivotally mounted on the fuel inlet, the charge of mercury in said switch defining the switch actuator, pivoting of said fuel cap to said first position to close the fuel inlet causing said charge to flow in a direction to open the switch and pivoting of said cap to the second position to open the fuel inlet causing the charge to flow in a direction to close the switch.
 3. A safety exhaust system as defined in claim 2, and further characterized in that said mercury switch comprises a vessel enclosing said charge of mercury, said vessel being mounted in said cap with one end thereof lower than the other end when the cap is in the first position, the pair of contacts within the vessel located adjacent the other end and above the level of the charge when the cap is in the first position, leads extending from said contacts externally of the vessel into connection with the electrical circuitry, pivoting of said cap to the second position causing the mercury charge to flow to the other end of the vessel and complete an electrical circuit through said contacts.
 4. A safety exhaust system as defined in claim 1, and further characterized in that said switch means is mounted in said fuel inlet, said fuel inlet included an opening for injection of fuel, a recess adjacent said opening, fixed contact means extending into said recess, said actuator being a member slidably received in said recess, spring means biasing said actuator outwardly of the recess to a position where a portion thereof extends from the fuel inlet, contact means carried by said actuator to close said fixed contact means upon biasing of the actuator to said last mentioned position by the spring, said fuel cap being effective to depress the actuator when moved to the first position thereof to open the fixed contact means.
 5. A safety exhaust system as defined in claim 4, and further characterized in that said fixed contact means includes a pair of spaced apart contacts, the contact means on the actuator including an electrical conductor which engages both of said contacts upon biasing of the actuator by the spring to thereby close the circuit through the fixed contacts.
 6. A safety exhaust system as defined in claim l, and further characterized in the provision of a pair of electrical signalling devices connected in parallel, a double-throw, double pole vane-type switch interposed between said signalling devices and said electric power means, said vane-type switch normally biased in one direction to close a circuit through power to one of the signalling devices, said vane-type switch being positioned in the flow path of the blower fan and operative upon impingement of gas flow thereon from the fan to open a circuit through power to said one signalling device and close a circuit through power to the other signalling device, and operative upon deenergization of the blower fan to revert to the original position.
 7. A safety exhaust system as defined in claim 1, and further characterized in the provision of separate additional switch means in said electrical circuitry operative upon closure thereof to energize the blower fan.
 8. A safety exhaust system as defined in claim 7, and further characterized in that said separate additional switch means comprises an ignition switch having a first position and a second position, an electric starter motor for starting the boat engine, first electrical circuitry connecting said blower fan to said electric power upon actuation of said ignition switch to the first position, second electrical circuitry connecting said starter motor to said electric power upon actuation of said ignition switch to the second position, electrically actuated stop means preventing actuation of the ignition switch to the second position immediately following actuation thereof to the first position, electrical timer means, said first electrical circuitry connecting said timer means to said electrical power and initiating operation thereof upon actuation of said ignition switch to the first position, said timer means effective to actuate said stop means to permit actuation of the ignition switch to the second position after a preselected time interval.
 9. A safety exhaust system for the engine compartment of a boat comprising an ignition switch having a first position and a second position, an electrically operated blower fan mounted to exhaust fumes from the engine compartment, an electric starter motor for starting the boat engine, electric power means, first electrical circuitry connecting said blower fan to said electric power upon actuation of said ignition switch to the first position, second electrical circuitry connecting said starter motor to said electric power upon actuation of said ignition switch to the second position, electrically actuated stop means preventing actuation of the ignition switch to the second position immediately following actuation thereof to the first position, electrical timer means, said first elec-trical circuitry connecting said timer means to said electrical power and initiating operation thereof upon actuation of said ignition switch to the first position, said timer means being effective to actuate said stop means to permit actuation of the ignition switch to the second position after a preselected time interval, said electrically actuated stop means comprising an electric solenoid having an extensible and retractable plunger, and a stop element on the ignition switch, said solenoid plunger being in registry with the stop element when the solenoid is deenergized and moving out of registry with the stop element upon energization of the solenoid to permit actuation of the ignition switch to the second position.
 10. A safety exhaust system as defined in claim 9, and further characterized in that said timer means comprises an electrical heater element in said first circuitry, a bi-metal strip in series with said heater element and located adjacent thereto to receive heat therefrom, said bi-metal element having a portion normally closing the circuit through said blower fan, said bi-metal element deflecting after being subjected to heat from the heating element for a predetermined time to open the circuit through the blower fan and close the circuit through the electrically actuated stop means.
 11. A safety exhaust system as defined in claim 9, and further characterized in the provision of an emergency switch between said starter motor and electric power bypassing the ignition switch to permit energization of the starter motor under emergency conditions.
 12. A safety exhaust system as defined in claim 9, and further characterized in the provision of a pair of electrical signalling devices connected in parallel, a double-throw, double-pole vane-type switch interposed between said signalling devices and said electric power means, said vane-type switch normally biased in one direction to close the circuit through power to one of the signalling devices, said vane-type switch being positioned in the flow path of the blower fan and operative upon impingement of gas flow thereon from the fan to open a circuit through power to said one signalling device and close a circuit through power to the other signalling device, and operative upon deenergization of the blower fan to revert to the original position.
 13. A safety exhaust system as defined in claim 9, and further characterized in the provision of separate additional switch means in said electrical circuitry operative upon closure thereof to energize the blower fan. 